1. Field of Invention
This invention relates to a fluid turbine structure which is used to generate electrical power by exposure to wind, tidal or ocean currents.
2. Description of Prior Art
With sources of energy, such as petroleum, natural gas and the like, being rapidly depleted throughout the world, either new sources of such energy must be found or alternative sources must be developed to fulfill the energy requirements for a highly technical society. Natural, nonpolluting, inexhaustable sources of energy, such as the wind, the tides, and the ocean currents can fulfill these needs.
U.S. Pat. Nos. 2,153,523 and 2,177,801 each illustrate the use of a wind driven double impeller for simultaneously rotating the field and armature windings of an electrical generator in opposite directions to double power production. The windings of the generator are connected to coaxial shafts which are driven in opposite or counterrotation by oppositely curved wind impellers. The impellers have opposite curvatures so as to turn in opposite directions when positioned normal to the direction of the wind by a vane.
Twin impeller wind machines have been able to provide more electrical power because of their inherent design. However, in the construction of twin impeller wind machines, one impeller has always been placed behind the other in parallel, vertical planes. Accordingly, both impellers must get their energy from the same wind field while rotating in opposite directions which is inefficient and causes undesirable centrifugal forces.
Furthermore, many attempts have been made to impart specific designs to the impellers so that they can spin in light as well as strong fluid currents. Such impellers have taken the form of exposed air foils, sails and paddles. However, many of these rotor structures are inefficient because as they rotate away from the fluid force, they also must return to their starting point and therefore, must cut back into the source of fluid, which tends to retard their rotation.
It will be appreciated from the above discussion that fluid powered turbines have mainly been machines placed in fluid currents to rotate from the direct force of that current as it moves past a rotor or impeller that is connected to an electrical generator. Little has been done in the way of molding, shaping, directing, or increasing the velocity of the fluid upon the rotor arrangement. In theory, the power available from a fluid current is proportional to the cube of the fluid current velocity. If the existing fluid velocity could be doubled, the power output would multiply by a factor of 8. An increase of 5 m.p.h. of the impinging fluid upon the rotor wherein the initial fluid velocity is in the range of 15 - 30 m.p.h., would result in doubling the power output. Therefore, the most powerful fluid driven machine would be one in which means are provided to increase the velocity of the arriving fluid and which is designed for maximum efficiency.